New to the message boards. I have a 87 d150 with slant six with a three speed with OD. My question is, there is a tube that runs from the back of the engine at the top, down and along the block ti the front, connects to a rubber hose than connects to another tube that runs to the first cat. Mine has rusted thur and now I have a bad exhaust leak. What is this tube and do I need it? Can I just plug the holes with pipe plugs? Any help would be great

The previous rendition of the tube was the air charge tube that takes unspent exhaust gas and dumps it into the cat to burn more for cleaner emissions (the late-70's vehicles had it run to the air cleaner....).

If your area requires all the smog equipment to be present or functional then yes, you have to have it. If you have exemption (rolling or not), you can cut the tube and flatten it, then fold it over on itself a few times to plug the hole.

-D.Idiot

Thanks for the info. No emmisons check here. Only problem is not enuf tubing left to fold over that's not rusted. Any ideas on the best way to remove it and plug the holes

Hello Hoosier lol. I went to autozone and ordered a new down pipe for an 81, it gets rid of the cat and all that jazz. It will however have a hole in it for an O2 sensor but you can just find a plug and weld it shut. works like a charm, bolts right in too. I ran from it to an autozone thrush welded and make a nice low tone w no drone. Take a look through the board some there are lots of pictures with and without the air pumps/cats/ etc. Good luck and keep us posted.
Pohlman

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225, Offenhauser, Holley 350, A833OD, 3:55, GM HEI,99 Durango starter
BOOSTED! WH1C, BIG FMIC, 10#
Operation Noble Eagle 03-05
Operation Iraqi Freedom 05-07
Operation Enduring Freedom 12- 13

Don't weld it.

Just plug it so that if you ever want to tune with a wide-band O2 sensor you'll have a spot to put the sensor.

This oil pan plug will fit the sensor threads:

Dorman 65220 oil pan plug (18mm x 1.5 thread, 19mm hex head)

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

I'm sorry I should have been more clear, I too used a plug but put a tack weld on both sides so it won't work loose from hot/cold cycles. And if I remember right that plug wasn't a typical thread bc I went to the local u-pull and just tried to find an old O2 sensor for it w no luck. Never thought to look if the 81 had an O2 for the downpipe.

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225, Offenhauser, Holley 350, A833OD, 3:55, GM HEI,99 Durango starter
BOOSTED! WH1C, BIG FMIC, 10#
Operation Noble Eagle 03-05
Operation Iraqi Freedom 05-07
Operation Enduring Freedom 12- 13

On the cat you can get a plug at your local auto parts store (or look through the Orange Dorman drawers for the correct plug). On the back of the head you have a couple of options: 1) If you have a local junkyard with 70's mopars in it, the mid-late 70's V-8's had this port on their heads as well, and if they didn't need the charge tube there is a stock metal tab that they bolted to the head instead- that's best case scenario. 2) Would be to get a pipe cap from home depot (I think it's close to 3/8".), clean out the port, goop with copper RTV plug and reinstall whats left of the tube to hold it in place. Wait over night and drive it...the beauty of the port is it's in a 'lazy' spot on the manifold so it should cake itself with carb pretty quickly and seal itself further.

-D.Idiot

Just checked the azone store and the downpipe is $103, no mention of an O2 port but when you look up o2 you get 4 choices and 2of them say M18 threads. Cheapest o2 is $14. Or just use the mentioned plug. I added a new picture in my build thread today that shows the OE cat and lean burn system like yours. If you look through it you'll also see the azone downpipe and the plugged port.

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225, Offenhauser, Holley 350, A833OD, 3:55, GM HEI,99 Durango starter
BOOSTED! WH1C, BIG FMIC, 10#
Operation Noble Eagle 03-05
Operation Iraqi Freedom 05-07
Operation Enduring Freedom 12- 13

thanks for the info. will have to wait until this weekend to work on it, long hours at work. I have another ? is there a way to rais the front end. My truck pitches way down in the front. there is a big diferance in hight. the back end sets alot higher. Also does anyone know were I can get a whole dash. the owner before me was a firefighter and mounted all his stuff to the dash, so now i have a dash with holes and would like to replace it.

Got the exhaust leak fixed. Put a pipe plug in the converter, and welded over the hole on the plate that mounts the tubing to the head. Thanks for the info. Now on to other projects on the truck

That's great news. See if you can find your option codes on the underside the hood and post up what you have.

Greens fork! It's like we are on the opposite borders of the state. I don't know as I'd want to eat anywhere that has green forks

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225, Offenhauser, Holley 350, A833OD, 3:55, GM HEI,99 Durango starter
BOOSTED! WH1C, BIG FMIC, 10#
Operation Noble Eagle 03-05
Operation Iraqi Freedom 05-07
Operation Enduring Freedom 12- 13

Will look tomarrow for the codes when its light out.
The local choke and puke may green forks, you are welcome to stop and check.

Looks like I have some work ahead of me this weekend. Got a bad miss now. Started on the way home from work.